This invention relates to an unwinder for a roll of web material, and, more particularly, to an automatic splicer for splicing the web of a first roll to the web of a second roll.
Unwinders are commonly used to unwind a roll of wound web material so that the web can be processed by equipment downstream of the unwinder. For example, in the paper converting field a large parent roll of paper is unwound and advanced to a rewinder, which perforates the paper to form individual sheets and rewinds the paper into consumer-sized logs or rolls of bathroom tissue or paper towels. Examples of such rewinders are described in U.S. Pat. Nos. Re. 28,353, 4,723,724, 5,104,055 and EPO Patent No. 0 694 020 B1.
When a parent roll is completely unwound or almost completely unwound, or when it is desired to change the parent roll for any other reason, the parent roll must be removed from the unwinder and replaced with a new roll. The leading end of the new roll must be joined or spliced to the trailing end of the old roll so that a continuous web is advanced through the downstream equipment.
Co-owned U.S. patent application entitled "Center Drive Unwind System," Ser. No. 08/838,278, filed Apr. 16, 1997, now U.S. Pat. No. 5,906,333, describes a center drive unwinder which automatically replaces parent rolls and splices the trailing end of the old roll and the leading end of the new roll.
Many unwinders are not center driven. Instead, the roll is rotatably mounted on the unwinder, and a belt driven mechanism engages the surfaces of the roll to rotate the roll and to unwind the web.
U.S. Pat. No. 5,730,389 describes a device for changing and splicing rolls on a belt-driven unwinder. Two rolls are mounted on movable carriages. The first roll is unwound by the belt, and the second roll is laterally offset from the first roll. The leading end of the second roll is retained by a suction member on the carriage. When the rolls are to be changed, a second suction member and a blade are moved against the web to cut the web and hold the trailing end of the web against the second suction member. The second suction member and the blade are then moved away from the web path. The carriages are moved to bring the second roll into the unwinding position, and the leading end of the second roll is joined to the trailing end of the first roll.